The ingredients are simple: onions, garlic, eggplant, peppers, zucchini, tomatoes & lots of olive oil. However, each French cook seems to have her own way of putting them all together. Some like the vegetables chopped small like a dice, but I was taught & prefer to cut mine in large chunks.
I have deviated slightly from the original recipe, as I like to put the eggplant in the oven & roast it, seasoned with salt & pepper & coated in olive oil. I think it has a much better flavor this way.
After that, I pretty much follow what I was taught & that is to sauté each ingredient separately in olive oil, seasoning each as you go. I like to add red & yellow peppers, too, although, green are the traditional choice.
I tend to sauté the onions & garlic last, then add the tomatoes, simmering them, as if making a tomato sauce. At this point I had some tomato paste.
Because my neighbors so kindly give me so many lovely herbs from their gardens, I have added fresh bay leaves & thyme to this batch. But other times I might add hot pepper flacks to give a little kick. This, however, is decidedly not French.
The final step is to add everything together. I have made this batch for a later date, at which time, I will reheat it in the oven until it is bubbly. To serve, remove the bay leaf & thyme & add chopped fresh basil. It is good as a side dish or as a main course served with rice or pasta.
A funny story, just to show how important ratatouille is to this region. I was chatting with a young mom who was feeding her baby from a baby food jar. I asked what the child was eating. " His favorite, ratatouille! " Seeing my surprise, she showed me the jar. It had all of the same ingredients: onions, garlic, eggplant, peppers, zucchini, tomatoes, even olive oil. She on the other hand was quite surprised, even shocked, to learn that children in the United States do not grow up eating ratatouille from the very beginning, in baby food jars.